Issue #3484571 by grimreaper, pdureau, mh_nichts: Manage layouts regions

src/ExampleSyntaxConverter.php

@@ -68,6 +68,13 @@ class ExampleSyntaxConverter implements ExampleSyntaxConverterInterface {
       'type',
       'value',
     ];
+    $in_layout = (isset($renderable['theme']) && \explode('__', $renderable['theme'])[0] === 'layout');
+    $layout_allowed_render_keys = [
+      'attached',
+      'attributes',
+      'theme',
+      'settings',
+    ];
     foreach ($renderable as $property => $value) {
       if (!\is_string($property)) {
         continue;
@@ -76,6 +83,10 @@ class ExampleSyntaxConverter implements ExampleSyntaxConverterInterface {
       if ($in_html_tag && !\in_array($property, $html_tag_allowed_render_keys, TRUE)) {
         continue;
       }
+      // Layouts are special.
+      if ($in_layout && !\in_array($property, $layout_allowed_render_keys, TRUE)) {
+        continue;
+      }
       if (\str_starts_with($property, '#')) {
         continue;
       }

tests/src/Unit/ExampleSyntaxConverterTest.php

@@ -33,6 +33,7 @@ final class ExampleSyntaxConverterTest extends UnitTestCase {
       'Not convertible' => self::notConvertible(),
       'Status messages' => self::statusMessages(),
       'Theme image' => self::themeImage(),
+      'Theme layout' => self::themeLayout(),
     ];
     foreach ($data as $label => $test) {
       yield $label => [
@@ -209,4 +210,62 @@ final class ExampleSyntaxConverterTest extends UnitTestCase {
     ];
   }
 
+  /**
+   * Theme layout.
+   */
+  protected static function themeLayout(): array {
+    $value = [
+      [
+        'theme' => 'layout',
+        'my_region' => [
+          'markup' => 'my markup',
+        ],
+        'attributes' => [
+          'class' => [
+            'my-class',
+          ],
+        ],
+      ],
+      [
+        'theme' => 'layout__my_theme',
+        'my_region' => [
+          'markup' => 'my markup',
+        ],
+        'attributes' => [
+          'class' => [
+            'my-class',
+          ],
+        ],
+      ],
+    ];
+    $expected = [
+      [
+        '#theme' => 'layout',
+        'my_region' => [
+          '#markup' => 'my markup',
+        ],
+        '#attributes' => [
+          'class' => [
+            'my-class',
+          ],
+        ],
+      ],
+      [
+        '#theme' => 'layout__my_theme',
+        'my_region' => [
+          '#markup' => 'my markup',
+        ],
+        '#attributes' => [
+          'class' => [
+            'my-class',
+          ],
+        ],
+      ],
+    ];
+    return [
+      'value' => $value,
+      'expected' => $expected,
+    ];
+  }
+
 }